The Siege Tunnels were carved out by
the Merchant Marine to defend Gibraltar from the
mainland during the Great Siege of 1779
to 1783. The original goal of the tunnels was to get
a cannon on the northern face of the rock known as
the Notch. Originally the tunnel was only 82 feet
in length, but by the end of World War II, the tunnels
had reach a winding distance of over 30 miles.

These tunnels seem to go on forever. Entering on
one end of the rock, you almost literally go to the
other side.

Holes for cannons are carved into the rock all
along its mainland-facing side. As you
cross into Gibraltar, look closely and you should be
able to spot these holes in the rock face. (A wet cloth was hung from the rod
above the cannon to prevent sparks flying back and
igniting the powder.)

Some levels of the tunnels are only accessible to
the extremely foolish.